Where possible, leave the wrench on the valve so a quick closing of the valve can be made in the event of an emergency.
在可能的地方，把扳手留在阀门上，以便在紧急情况下可以迅速的关闭阀门。
2
They are designed to provide a secondary seal in the event the cylinder valve develops leakage through the valve seat.
它们是设计用来在钢瓶阀门通过阀座产生泄漏的情况下提供一个二次密封。
3
The upper master valve is used on a routine basis, with the lower master valve providing backup or contingency function in the event that the normal service valve is leaking and needs replacement.